By Derex Q. Zellars | Environmental Scientist
Traditional methods used to protect plants from disease have been largely based on the use of chemical fungicides. Applications of fungicides can have drastic effects on the environment and the human population and are now being applied at a much higher rate than any time before in history. The long-term consequences of fungicide use are creating a resistant strain of the targeted organism.
Benefical microorganisms and their activities are an indispensable component for the quality, maintenance, and improvement of soil. The multifaceted functions played by the microorganisms contribute directly, as well as indirectly, to soil quality. Bacteria help in growing healthy plants (i.e. free of disease) as well as nourishing plants with the essential nutrients through various activities.
These activities are labeled as a “biological control”. Biological control involves the use of beneficial microorganisms and products such as metabolites, that reduce the negative effects of soil,and water-borne plant pathogens and promote positive responses by the plant. Some activities that help improve plant health are an indirect mechanism where potent antibiotics are produced and released in the presence of pathogens entering the rhizosphere. By preventing these pathogens from entering, and subsequently colonizing the roots, plants can continue the natural growth cycle without any interruptions.
Bacillus strains have many applications, including foliar applications to guard against pathogens that are transported by wind or water to the foliage. It is equally important to look at how pathogens are evolving based on the array of chemicals introduced each day. When nutrients are sprayed onto the foliage, beneficial bacteria must also accompany these nutrients. Pure bacterial species provide a safeguard; there is no direct competition with other microorganisms that could eventually lead to a toxic environment if different genus and species are combined.
Scientific research has confirmed that small amounts of nutrients are absorbed through the leaf tissue but the remainder becomes a source of nutrients to the bacteria1, aiding in the overall protection of the plant. Beneficial microorganisms should be applied for an extended period of time to increase their efficacy. Increased yields and the overall quality will be an indicator as to how well a particular species will perform under certain environmental conditions.
Using beneficial microbes provides a preventative option, versus a curative method, that is slow and deliberate with results that are more stable, consistent, and lasting compared to chemical controls. As plants develop, stress is naturally incurred, which makes many plant varieties susceptible to disease. Foliar fed plants can alleviate this stress by delivering nutrients across the cell membrane and depositing nutrients to the metabolic sites of each cell. Benefical bacteria are not trans-laminar, however, any anti-fungal or bacteria substances released are bound to a chelating agent such as nano-molecules. The anti-fungal substances now become systemic, aiding in the natural defenses of the plant.
The overall importance of foliar feeding is to bypass a complex soil matrix that can tie up nutrients causing nutrient deficiencies. The absorption rate is immediate when foliar feeding applications are implemented.
1 J. Benton Jones, Jr. (1997). Plant Nutrition Manual. Boca Raton: CRC Press